Liquid crystal display apparatuses have been rapidly spreading as alternatives of conventional CRT displays since the apparatuses have characteristics such that they are small in power consumption, light, and thin. As illustrated in FIG. 5, an example of ordinary liquid crystal display apparatuses is a liquid crystal display apparatus having a polarizing plate 102A on the light incident side, a polarizing plate 102B on the light outgoing side, and a liquid crystal cell 104. The polarizing plates 102A and 102B are each a member constructed in such a manner that the member selectively transmits only linearly polarized light (schematically illustrated by each arrow in the figure) having an oscillation face exhibiting a predetermined oscillation direction. The plates 102A and 102B are arranged to face each other in a crossed nicol state that their oscillation directions become a right angle to each other. The liquid crystal cell 104 contains a large number of cells corresponding to pixels, and is arranged between the polarizing plates 102A and 102B.
Liquid crystal display apparatuses have, as a peculiar drawback, a problem about viewing angle properties. The problem about viewing angle properties is a problem that properties such as the contrast or color tone is varied between the cases: where persons watch a liquid crystal display apparatus from the front thereof, and the case where persons watch the liquid crystal display apparatus along a direction oblique thereto. This is because the liquid crystal cell used in the liquid crystal display apparatus exhibits birefringence, and because the apparatus has two polarizing plates arranged in a crossed nicol state.
In order to overcome the viewing angle property-problem, various techniques have been developed up to the present time. A typical method thereof is a method of using a retardation film having a predetermined birefringence. This method of using a retardation film is a method of arranging a retardation film which exhibits a predetermined birefringence between a liquid crystal cell and a polarizing plate, thereby improving the viewing angle properties.
The above-mentioned method of using a retardation film to overcome the viewing angle dependency is useful since the birefringence of the retardation film is varied in accordance with the kind of the liquid crystal cell, thereby making it possible to overcome the viewing angle dependency of liquid crystal display apparatuses in which liquid crystal cells having various optical characteristics are used. Such a retardation film is disclosed in, for example, Patent Documents 1 and 2.
As disclosed in such as Patent Documents 1 and 2, the above-mentioned retardation film is generally a film having a liquid crystal layer where a liquid crystal material is aligned. In order to align a liquid crystal material in a liquid crystal layer, it is necessary to form the liquid crystal layer on an alignment layer having alignment regulating force for the liquid crystal material. Therefore, any retardation film having a liquid crystal layer has an alignment layer as an essential constituent. As such alignment layers, rubbing films which exhibit alignment regulating force by rubbing treatment have widely been used. In recent years, however, attention has been paid to photo alignment layers in which alignment regulating force is expressed by optically aligning treatment (for example, Patent Document 3). Such a photo alignment layer can express alignment regulating force by non-contact optically aligning treatment; therefore, the film has advantages that alien substances are not generated by the aligning treatment and further no restriction is imposed onto the direction in which alignment regulating force is expressed even when a long retardation film is produced.
Incidentally, the above-mentioned retardation film is usually produced by a process of coating an alignment layer and a liquid crystal layer onto a long transparent substrate; therefore, in many cases, the film is in the form that the film is wounded around a winding core in a distribution process. In such a form that the film is wounded, portions of the retardation film are overlapped with each other, thereby applying external stress to the retardation film. Thus, there arises a problem that members such as the alignment layer, the liquid crystal layer is injured or damaged. In particular, in the case of using, as the alignment layer, or the above-mentioned photo alignment layer, the photo alignment layer has a problem of being easily damaged by external stress since the photo alignment layer has a lower mechanical strength than conventional rubbing films or the like, and since the film needs to be made thin.
Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 8-338913
Patent Document 2: Japanese Patent Application National Publication No. 2002-533742
Patent Document 3: JP-A No. 2002-90532